Im trying to install windows 7 on a second partition in ssd (windows 8.1 is installed in the first partition) but i keep getting this message from this forum thread: http://www.windows-n...ration-manager/ but i have no idea how to do the solution written there. I have unallocated space ready in my second partition to install windows 7 in it. The disk is GPT. I have been trying to make UEFI Bootable (GPT) usb sticks using rufus that i can then use to install my windows7 BUT every time i get stuck in this problem and i don't understand how the solution works. task sequence with 64 bit boot image? etc. my motherboard is asus z97 gamer pro. There are bunch of uefi/cms/secure boot options currently uefi is enabled. I am pretty new to this stuff and my goal is to dualboot windows 7 and 8 64bit both inside 1 ssd into different partitions. Edit: Was able to install win8 as a dualboot to ssd's third partition after removing hdd, didn't try with the above method though. Also running diskpart > list disk > select disk x > /clean and doing Bootrec /FIXBOOT , Bootrec /FIXMBR from recovery menu cmd (shift+f10) might have helped.